1. Field of the Invention
The present invention provides a membrane gas generator which is used in conjunction with bulk nitrogen storage to be responsive to changes in customer demand patterns while avoiding undue increases in generator and operating costs.
2. Description of the Background
Membrane process are used with increasing frequency in the production of inert atmospheres from air, wherein the oxygen content in a feed air stream to the membrane is decreased by permeation from a high pressure side to a low pressure side. However, it is very difficult to size the generator for customer need, as the demand is not straightforward. For example, demand often changes considerably both in the very short term, i.e. at ten minute intervals, and in the long term, i.e., with the change of seasons and from year to year. Of course, this difficulty is not specific to membrane process, but is applicable to any small-on site plant serving the needs of a single customer.
Although various methods have been proposed for overcoming this difficulty, all suffer from various disadvantages. For example, inert atmospheres have been produced at a pressure higher than required by customer need with storage of excess production in a buffer or storage tank during low demand periods with subsequent release during peak demand periods.
While, these solutions have been somewhat helpful in adapting to customer demand, in most cases it remains necessary to use an oversized generator, which can be detrimental to the process economy when annual usage of the facility is low.
Thus, a need exists for a membrane generator which exhibits increased flexibility and productivity and is responsive to changes in customer demand pattern while avoiding undue increases in generator and operating costs.